Compilare: user.cpp: In function ‘void Add(Trie*, std::string&, int)’: user.cpp:74:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (pos == s.size()) ^ user.cpp: In function ‘int Words_with_Pref_X(Trie*, int, std::string&, int)’: user.cpp:87:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (pos == s.size()) ^ user.cpp: In constructor ‘InputReader::InputReader(const char*)’: user.cpp:12:37: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(buf,SIZE,1,input_file); ^ user.cpp: In member function ‘void InputReader::advance()’: user.cpp:53:41: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(buf,SIZE,1,input_file); ^